but just one day after the check was issued, khan was dead. an initial exam by the cook county medical examiner found the 46-year-old died of natural causes. >> the initial investigation didn't suggest anything suspicious about his death. >> reporter: then, came a phone call from a suspicious family member who has not been identified. >> they just felt like this didn't seem likely. it didn't seem like it could have been natural to them. >> reporter: a full toxicology test revealed khan had ingested a deadly amount of cyanide. and now, his death has been reclassified a homicide. >> logic would dictate, it's someone who could potentially get their hands on his $500,000. >> reporter: according to an internal police department document obtained by "the chicago tribune," khan came home from work on july 20th, ate dinner about an hour later, and eventually went to bed. he was later heard screaming, taken to the hospital and pronounced dead. >> if he ingested that cyanide at a dinner meal at home, that's willful. that's very cold-blooded, and it's in